A dialysis system is used as a substitute for the natural kidney functions of a human body. The dialysis system cleans the blood of the natural accumulation of bodily wastes by separating the wastes from the blood outside or extracorporeally of the body. The separated wastes are discharged and the cleansed blood is returned to the body.
The dialysis system consists of a dialysis machine, a dialyzer, a disposable blood tubing set and a supply of chemicals for producing a dialysate solution used within the dialyzer. The dialyzer is used with the dialysis machine to separate the wastes from the blood. The dialyzer includes a porous membrane located within a closed housing which effectively separates the housing into a blood compartment and a dialysate or filtrate compartment. The blood removed from the patient flows through the disposable blood tubing set and the blood side of the dialyzer. The dialysate solution prepared from the chemicals is passed through the dialysate side of the dialyzer. The wastes from the blood pass through the membrane by osmosis, ionic transfer or fluid transport into the dialysate and, depending upon the type of dialysis treatment, desirable components from the dialysate may pass in the opposite direction through the membrane and into the blood. The transfer of the wastes into the dialysate cleanses the blood while allowing the desired components from the dialysate to enter the bloodstream.
The transfer of blood between the patient and the dialyzer occurs within a disposable blood tubing set. The blood tubing set and the dialyzer represent a closed extracorporeal path through which the patient's blood travels. The blood tubing set includes an arterial line for drawing blood from a patient and a venous line for returning the dialyzed blood to the patient. Before the blood tubing set and the dialyzer can be used in a dialysis treatment, both must be primed with a sterile saline solution to remove air from the extracorporeal circuit.
The dialysate which flows through the dialysate compartment of the dialyzer is typically prepared by the dialysis machine within a dialysate flow path of the machine. The dialysis machine mixes purified water with chemicals such as bicarbonate and acid within the dialysate flow path and heats the prepared dialysate before pumping it to the dialyzer. The resulting dialysate mixture has beneficial chemical properties which allow the dialysate to attract the waste products from the patient's blood and draw the waste products through the dialyzer membrane. However, the same chemical properties which allow the dialysate to perform its cleansing function also tend to attract microorganisms. Thus, it is typically necessary to clean and disinfect the dialysate flow path of the dialysis machine on a daily basis before any patients are connected to the dialysis machine.
The cleaning and disinfecting process may take up to several hours or more depending on the type of disinfection process used. The typical approach to cleaning and disinfecting a dialysis machine is for a worker to start the cleaning/disinfecting process early in the morning so that it will be completed prior to the arrival of the first patient. However, such an approach typically requires the worker to arrive at a very early hour, particularly since the blood tubing set and the dialyzer can not be connected to the dialysis machine and primed until after the dialysate flow path has been cleaned and disinfected.
The requirement of cleaning and disinfecting the dialysate flow path is often governed by a regulatory agency and thus can not be avoided by a hospital or dialysis clinic. Therefore, although the majority of the cleaning and disinfecting process is typically performed automatically by the dialysis machine once it has been initiated by a worker, the requirement that the process be performed each morning, together with the length of time required to perform the process, represents a substantial burden on hospitals and clinics in the form of increased labor costs.
These and other considerations have contributed to the evolution of the present invention which is summarized below.